Update (12-21-19): An Asian giant hornet was recently discovered just south of the Canadian border in the town of Blaine, Washington. The dead specimen, collected by the Washington State Department of Agriculture (WSDA), was confirmed as Vespa mandarinia. A live specimen, believed to be the same species, was also seen at a nearby hummingbird feeder.
Back in August, three other specimens were found just north of the border in Nanaimo, B.C. There, the nest was eventually found and destroyed, but officials and beekeepers remain vigilant.
The hornets, which can reach nearly two inches in length, can decimate a honey bee hive, sometimes in a matter of hours. They are skilled hunters that prey on many types of insect, but honey bee hives are convenient for the voracious predators.
Like most hunting wasps, their numbers peak in late summer, so they they are commonly seen in July through October. They have distinctive orange-yellow heads with large black eyes, nest in inconspicuous underground cavities, and can deliver a powerful sting.
Curiously, the WSDA advises residents to stay away from the hornets, but requests a photo should you happen to see one.
The following post was written about beekeeping in France with the closely-related Asian hornet, Vespa velutina.
After I wrote about the Asian hornet (Vespa velutina) entering Great Britain, a beekeeper living in southern France wrote to me about his five-year struggle with these aggressive bee eaters.
Michael Judd, originally from England, keeps ten hives at an elevation of 789 meters (2588 feet) under a small wild-flower-covered mountain near the village of St. Vallier. These higher elevation hives have remained free of the hornets. But he also keeps a couple of small hives in his backyard where the hornets thrive. Here in his backyard is where he has been experimenting with control measures.
Sadly, Michael had an inauspicious beginning with hornet control. His local bee association in cooperation with the government started a program to research solutions to the hornets. Michael signed up for an experiment and agreed to follow all the rules. As a result, he lost all four of his garden hives.
Furious with the deal, Michael asked for compensation. Although none came, he was introduced to a local beekeeper with 70 colonies who builds hives and raises queens and nucs. Even better, he is actively developing ways to deal with hornets. Happily, the ensuing friendship outweighed the loss of Michael’s experimental colonies.
Here is Michael’s take on controlling Asian hornets.
I have lived with Asian hornets for about five years. At first, I lost five hives, then I improved the defenses and so did the bees
The first thing to know about the Asiatic hornet is that, unlike its European counterpart, it hovers in front of a bee hive. This makes for the first line of defense for the beekeeper. A badminton racquet makes it really easy to swat them. I am fortunate that I can have bee hives in my garden so my physical presence gives me the ability to visit often during the day and swat them. A more remote location makes this somewhat difficult.
The Asian hornet life cycle
Asian hornets all die off at the end of the summer, in my case around the end of October. A mated queen or queens then go and hide in a tree or in the ground. They emerge in spring (about April) and search for a place to make a temporary nest. This is a small one, possibly the size of a golf ball. She lays a few eggs there, yielding 6 or 8 hornets. They then search for firstly food and secondly a place, usually high up a tree, to make the main nest.
The hornets are said to only want protein at the end of the summer. Before that they feed just like bees and sometimes together on the same plant. I spotted them in April (South of France near Nice) on a plant that was flowering.
Trapping the queens
I put out a trap made out of a plastic water bottle with a bought product that is a special hornet attractive. This is important, as catching the queens at this time reduces the chance of a large colony being formed. At his time of the year I catch and also swat a reasonable number of hornets, sometimes up to 10 a week. Once the main colony has been formed, with a nest that can be several feet round, there seems to be little chance of finding the nest, which is usually high up in a tree.
For a while during the early summer the hornets seem to disappear. But not completely, as from time to time I see one or two around my hives at the other side of my garden. But by the time mid July/August comes along the hornets can be seen flying about the hives.
The attack
The hornet hovers outside the hive and awaits a departing or returning bee and catches it in mid air. It takes the bee to a tree where it takes the wings and head off and then the hornet takes the bee to its nest.
The hornet will only go into the hive when the bees are very weak, not flying, and unable to attack in numbers. I have seen the bees on an entrance or inside the muzzle (see below) attack and kill a hornet, so generally the hornets do not seem to like going in the hive. However, I notice that at this time of year, mid to late September, the hornets are desperate for protein and they get more bold.
How the honey bees react
The reaction of the bees is to feel trapped in the hive. There is a siege going on and their flights are down to an unsustainable minimum. Without any action, the colony will simply reduce in strength until it fades away. In my first year, I found 2 or 3 very small (the size of a tennis ball) swarms in the garden. I got the impression they swarmed out of total desperation. At other times the bees ate all their stores and simply died.
I have noted and read on blogs that up to about 3 hornets around a hive allows the bees to more or less fly normally, but any more than that forces the bees to stay in the hive.
Control measures
First, I put out several traps. Some made of plastic water bottles and some purpose-built wasp traps. I use two different liquids. The first is an “attractive” bought from my bee association. Sometimes I add a little honey-soaked beeswax. The second is a mixture of white wine, apple vinegar, and cassis. Both of these work very well. A lot of people recommend beer, but I find that it does not work. This year I put both mixtures out in 6 traps (3 each). At the height of the rush, I was catching between 10 and 20 a day.
The next thing I do is to reduce the entrance to the hive. This, of course, makes it easier for the bees to defend their entrance. Then I add what the French call a “muzzle.” It is a wire contraption (see photo) with the holes in the wire measuring 13 mm square (0.5 inch). This allows the bees to enter, but the much bigger hornets are very reluctant to enter as the bees attack them inside. This allows the bees a safe area where they can see the hovering hornet, and either go the other way or exit later.
The bees’ line of defense
What I noticed with one of my hives which had Italian bees is that they set up a line of bees on the floor of the muzzle and this acted as a defense and landing and take off strip for arriving and departing bees. They ware also in position in large numbers to attack any hornet silly enough to get too close. It seems to take the bees about 20 minutes to kill a hornet. It is also interesting to note that a guard bee is often seen scouting around the hive after I have swatted hornets. The scout appears to give the “all clear” when she does not see any more hornets.
This year I noticed that the hornets, rather than hovering directly in front of the hive entrance while waiting for a returning bee, would hover underneath the hive. I found it therefore impossible to swat them with my badminton racquet. So I took a piece of old bed sheet and cut it to fit to the base of the hive and tall enough to get to the ground. I put a skirt on the back and front of the hive. This really seemed to annoy the hornets as they attacked the sheet and could not get to the bees. The result, for me, was they had to hover in front to the entrance and I could swat them easily.
I would also note that when I approach the hive with my badminton racquet, the bees would not react. I would calmly swat, say, a couple or more hornets and the rest would disappear. They are very frightened of me, it seems. The other thing I noticed was if, for example, there were three hornets in the area and I swatted all three, it would take over an hour before any hornets returned.
Everything taken together
The object of all the defenses is to make it more difficult for the hornet to be able to sustain an attack. To this end, I have been moderately successful as I have kept hives operating, harvested honey, and got the colony through the winter..
None of these measures on their own make much difference. However all measures together allowed me to keep the hive strong. In early spring I had 4 hives in my garden and I took 3 of them to another location where I keep most of my hives. At this location (16 kilometers away and 780 meters above sea level) for reasons unknown, there are no hornets yet, so I moved 3 away for safety.
Michael Judd
Here you can see hornet “muzzles” on the hives. The bees pass through freely, but the hornets are reluctant. © Michael Judd.
Here you can see a fabric skirt added to the front and back of the hive to prevent the hornets from hanging around underneath. This made it easier to swat the hornets. © Michael Judd.
The honey bees set up lines of defense to guard against the hornets. It takes about 20 minutes for the honey bees to kill one. © Michael Judd.
Excellent post! I assume it is only a matter of time before we have to add this pest to our list of predators. This summer I noticed very similar behavior in front of my hives from European Hornets. They hoover right in front of the hive and will take a bee right out of the air. There were not enough of them to become too much of an issue but I will make hornet traps this winter and have them on standby next year. Thanks Rusty for the follow up post about Michael’s success.
John
The Tetbury area here in the UK is only 40 miles from me and my hives and I have had a few sleepless nights worrying about what could become of them and what precautions I could take. France has been dealing with these marauders for 12 years now and I was curious to know what measures they had developed to keep their numbers down. Looks like I’ll be making some traps and wire cages this winter in time for spring just in case this sighting is not a one-off. The badminton racket is going on my Christmas list (thank you for the tip Michael!) but perhaps with a slight modification. My father being an electrical engineering and always up for modifying things, will be tasked with electrifying it – a bit like a giant battery powered fly-swatter! Let’s see how they like karma.
Hopefully I’ll never have to use it.
Philippa,
Good luck with the electrification. I have tried an electric mosquito racquet on the Hornets it does work although it seems to stun them and you need to find them to finish the job. I use it in the house when the hornet is on a window, which is rare. Someone, somewhere on the ‘net proposed a large electrified net behind or beside a hive. It was not deemed practical as most hives are in numbers and also in remote locations with no electricity. It is a good idea anyway.
I forgot to mention that I use these traps on my sentinel hives:
http://www.vita-europe.com/products/apishield-hornet-trap/
I’m considering expanding the number of traps to alternate hives. They are fantastic at catching and trapping wasps (I think you refer to them as yellow jackets?). They work by setting up false entrances and so far this year they’ve trapped 400+ in one trap!
I definitely recommend them for normal hives and they are supposed to help catch the European and Asian hornet too. I don’t think they make a trap for nuc boxes (yet) unless you put 2 wooden nuc boxes on one trap.
I just hope they don’t jump the ocean or if/when they do the practices to defend our hives is already developed.
Michael’s account of his experience with the Asian Hornet reminds me a little bit of an experience (on a much smaller scale) I had this summer. For the first time in my garden, I had “bee killers.” I saw only two and they were of different species.
The first one I noticed is known appeared to be a “Florida bee killer”, Mallophora bomboides. The second one appeared to be a “southern bee killer”, Mallophora orcina. I had never seen these insects before. I would be curious to know if anyone else has ever had experiences with these insects in their gardens.
I have a relatively small flower/herb garden (Richmond, VA, USA) which usually attracts a large variety of bees – and, many of them. In late July, I suddenly noticed the bee population had plummeted and I wondered what could be the cause of the decline…until I got a glimpse of the bee killers. I was eventually able to dispose of the bee killers (both of which had a honey bee in their grasp when I caught them), but very few bees have returned.
I would be interested to know if anyone else has ever seen these insects in their garden or around hives in their yard. I know they have been known to attack the hives of professional bee keepers. More information and pictures can be found at http://entnemdept.ufl.edu/creatures/misc/flies/bee_killers.htm
Amy
Amy,
Yes, these predators are around and I hear about them now and then; I’ve even seen a few. I always called them “robber flies” although both common names are in use. They are considered a minor predator on bees. There is a post with beekeeper photos of them.
Very interesting article about a pest that we might eventually have to deal with here in the US. I wonder if you could use a drone to attempt to find the hornet nest up in the tree? Maybe you could hit a few with the drone as it flies.
Tom,
Brilliant ! Could a drone carry a heat sensor?
Has anyone thought about configuring a queen excluder to fit over the entrances? I had that idea and would love to know if anyone could tell me whether or not the hornets can fit through that.
I think the problem is that the hornets snatch the bees out of the air as they are coming and going from the hive. They don’t need to go inside.
That is true Rusty, a queen excluder is too small as well as restricting the entrance to drones, etc. A reasonable thought but it has been tried and does not help.
My 2020 hornet log is here, I got off light a friend lost 4 out of 7 hives https://1drv.ms/b/s!AgZCpYNgfmp7hEQEJ0RutFEGglNm?e=F1R2pL
Some new ideas in the Asian hornet group I set up (please don’t join if you have no personal experiences to add) which may help others, end of its first year https://groups.io/g/asianhornet-beehiveprotection/topics
This guy (fast talker and in french) has some good ideas, other stuff on his channel https://www.youtube.com/watch?v=tgwrehpImQY
I was thinking of that also. But it may slow them down more than the wire mesh.
What puzzles me, how come the Asian Hornet has not made it into Western Europe on their own until recently in centuries/millenniums past. It is one land mass, no water bodies to stop them.
Also predatory wasps/hornets have been labelled as “beneficial” since they take a lot of pest insects. For this very reason wasps are protected by law in other jurisdictions.
Don’t get me wrong. I am a beekeeper myself. I just try to get a better understanding of the issue as a whole.
Dieter,
My guess is that unsuitable habitat stopped them, things like deserts and mountains. But once aircraft began carrying merchandise they could hide in, things like lumber and plants, then it was a piece of cake.
They actually came into France at Bordeaux on a shipment of timber from china.
Extremely useful tips – hope they won’t reach us in London next year but is only a matter of time.
John,
Thank you, although I would not call it a success yet, but only progress.
I am interested that you have seen European hornets starting to hover, where before they flew like a ‘plane, but still managing to catch a bee mid air!
I will investigate.
John,
Your comment about European Hornets hovering worried me greatly. I did not want to answer until I was sure. I do not see many here but they have been in evidence in the past weeks. I swatted a couple today to make certain. They are much easier to see and distinguish from the Asian ones, as their bodies are much more yellow and their legs are not yellow.
What I saw was distinctly different from the “fly by at speed” that I saw in years gone by. They were not hovering as well as the Asians. They were flying sideways in a right and left horizontal manner over a distance of 3 to 4 inches in front of the hive.
What worries me is whether they learned this by watching the Asian Hornet or much worse did they learn it from inbreeding. Whichever it is it is a worrying development. I am sure Rusty will see this!
Michael & John,
Interesting observations. The side-to-side movement is fairly common in wasps and it sometimes can be seen in honey bees that are in the process of robbing. It’s one of the ways you can often distinguish robber bees from orienting bees. But I think your observations deserve a closer look. Inbreeding among the hornets would definitely be worrisome.
Rusty,
Wow, It is most interesting that you connect the sideways movement to wasps and bee robbers. It is all getting worrisome, as you say.
Hi, I observed this behavior in European Hornets during last year’s heat wave here in Norway. I had moved 2 nucs to what I thought was a safe location as they were being robbed by my other hives. This was in the end of July 2018, and the drought had stopped all flow of nectar, so the bees were desperate, even though I fed them with both dry sugar and sugar syrup. The 2 nucs were robbed dry, so I moved them to my backyard. It did not take long before I noticed hornets hanging around the nucs and snapping bees in flight and on the landing board. As the bees were busy robbing each other, they were not as careful as they normally would be, and were an easy target. The hornets were hovering on the sides and in front of the nucs and swooping down to attack. The also were hiding under the hive stand. The bees eventually stopped flying, and were going around in kind of slow motion inside the hives. They actually seemed to act “depressed”. One of the nucs ended up absconding, I guess due to the stress of both the robbing and the predation. We do not have Asian Hornets in Norway, and European Hornets has not been in my area for decades, but last year they showed up everywhere, eventually also at my apiary.
I enjoy your newsletters and forward them on to fellow beekeepers.
I live in south Louisiana where we do not have Asian hornets – yet! Like the migration of “killer bees” from Central & South America and Mexico, hornets may show up here one day. To this end I say, “Than you for the information and the photos you share with beekeepers across the world.”
Looking forward to your continuing articles, and happy beekeeping,
SuEllen Lithgoe
CABA (Capital Area Beekeepers’ Assn) Member
Thank you, SuEllen. But remember, I couldn’t do this without the generous contributions from beekeepers everywhere. It really makes a difference.
MIchael,
Will you explain how you made the muzzles and how to attach them? I want to try this.
Danielle,
They are made by cutting and bending the wire into shape. I did this under the watchful eye of my bee Mentor ! So it is not my construction exactly.
When the wire is cut you round the bits on itself. Then add piece of ply wood as the landing area the bars of wood on top allow attachment to the hive. My mentor attached a metal L to the hive and clipped the wooden bars on that.
I actually used strong sticky tape reinforced but a couple of staples.
I could take a few close up photos of one, and ask Rusty if it was possible to post them on Honey Bee Suite.
Michael,
Photos would be great! Thank you.
Great article. I have large hornets here in western N. C. THAT ARE EATING MY BEES.
Love the badmitton racket. I would enjoy that.
My mentor in Virginia uses one of these, Electronic Racket Zapper:
It’s going on my list of things I need.
Very interesting account, thank you Michael, and I’ve circulated this link to our branch members. I wondered about the ‘muzzles’ – do they not slow down the bees as they go through, making it easier, presumably, for the hornets to grab one?
Actually, the wire does slow the bee’s entrance down sometimes. But you will not be surprised to hear that the bees enter and depart from angles I would never have thought of, ie they walk in from the side.
The other thing to notice if you look at the 2nd and 3rd photos you will see a line of bees from the actual entrance to the wire of the muzzle. This is the bees’ own defense system. The hornets rarely get close enough to the wire of the muzzle. If they do then the bees attack them in numbers and the hornet is dragged in to either suffocation by a hot ball of bees or of stings.
My hives are about 6 miles from the area where these little menaces have been found in Tetbury so I am on high alert
This article is very helpful just in case…..
Good luck Ted. The National Bee Unit have confirmed 6 other sightings all within 500 m of the original sighting so there must be a nest somewhere. They have set up a control centre and are working a 3 mile radius to find it. I fear it will be too late as the nest is most likely raising its queens for next year and some of them may have already left to find somewhere to hibernate. The NBU are recommending setting up traps now with 25% fish bait.
Philippa,
Thanks for the update. Let us know if they find the nest.
Radio Frequency Identification (RFID) chips have been attached to tens of thousands of bees in Australia, New Zealand and likely elsewhere to better understand their movements, life and behavior.
How about catching the odd hornet and attach a RFID chip to its back and let the hornet guide you back to its nest. Then position a flame thrower or other artillery and – game over! This way you don’t need observation posts, other than to catch the initial hornet. Bee hives may well serve as a bait.
If this was promising and efficient and done right away with sufficient resources you may even eradicate them again before they have spread too far.
Dieter,
Actually a very good idea. It would be worth the price.
So then, whom should the proposal be presented to?
After all, time is of the essence. If there are still hornets around this time of the year it would be worth a “proof of concept” trial.
If successful it may also be applied to other honey bee predators.
Philippa,
Fish bait is interesting. Why fish I wonder? I have heard there is the thought of using meat based bait with the Hornet taking it back to the nest. Sounds very good until you go to the next stage. (I am sure you are not suggesting simply feeding the hornets to keep them away from the bees.) What is the “poison” in the bait that then kill the hornets? The problem is, I believe and with respect, that this poison gets into all sorts of other species like birds and perhaps into bees as well.
There is an ant poison that the ant takes home and it is said that the nest dies completely. I have to say that that product appears to work.
Michael,
Maybe I’m missing something, but I didn’t read poison into this. I thought Philippa implied that the fish is used as an attractant in a trap, much like you use vinegar or cassis.
The advice I posted is what is being recommended by our government Department for Environment, Food & Rural Affairs’ National Bee Unit. The 25% fish bait is to be used in an Asian hornet trap.
http://www.nationalbeeunit.com/index.cfm?pageid=208
The idea being to trap and therefore kill any Asian hornets attracted to the trap – not to feed them (that’she the last thing we want to do!) There is significant evidence to suggest that traps placed now or early spring can make large gains in reducing yhe AH population. I presume that fish bait will be smelly enough to lure them in!
Dieter,
That is a fabulous suggestion! I have emailed your suggestion (and a link to this page – I hope you don’t mind Rusty) just in case they haven’t thought of it to the reporting email:
alertnonnative@ceh.ac.uk
Philippa
The specific chips they are using for bees may not be suitable. They had to be kept small and light enough so as to not hinder the bees in their endeavors. The range w/in which they can be read apparently is only 30 cm.
However, hornets could be saddled with heavier chips allowing more remote monitoring. After all its supposed to be a one way trip for them anyway. They are attaching all kinds of chips onto all kinds of animals, small and large, including fish and birds, in Banff National Park, Canada, and monitor them remotely. If this approach proves successful it may be modified and applied to other pests going after our bees as well.
http://www.zdnet.com/article/intel-and-csiro-create-rfid-bee-backpacks-with-edison/
http://www.hitachi.com/businesses/innovation/case_studies/hitachis-ultra-small-rfid-to-support-global-research-on-bees/
September 2016 – Asian hornet nest found and destroyed
Update from the National Bee Unit
An Asian hornet nest has been located and destroyed by experts in the Tetbury area. The nest was found at the top of a 55 foot tall conifer tree. Inspectors from the National Bee Unit are continuing to monitor the area for Asian hornets alongside local beekeepers. However to date, no live hornets have been seen since the nest was removed.
Let’s hope no Queens got away to hibernate. Still going to set up traps and electrify that badminton racket!
Any word as to how they found the nest 55 m up inside the branches of a coniferous tree? What size are these nests? Grapefruit size? Soccer ball? Bigger? How did they destroy it?
found it:
http://www.nationalbeeunit.com/public/News/news.cfm#176
those nests are gigantic!
More like 55 feet, I think.
Of course. 55 m would be more what you find in the redwoods in California. It’s more like 18 m. I overlooked that in the UK everything is still funny, whether it’s feet, Fahrenheit, or what have you.
Dieter,
That’s one way to look at it, but we’re about the only country left that doesn’t use the metric system. I think we’re the weird ones.
I think it was me that misunderstood. I am sorry that I missed the point of the fish.
Michael
No harm done.☺
Thank you, I got distracted as there have been thoughts of meat based lures with poison to kill off the nest. Any way I have just seen your latest post about a nest being found and distroyed. That is seriously good work. Please can we borrow that unit for France. If you have that sort of response in the UK then beekeepers have a chance – wonderful.
Michael
Rusty,
There are a couple of photos. Can I send them to you to upload?
Philippa,
I sent you an email.
Thank you everyone – and especially Rusty and Michael. What a brilliant community this is!
I have two bee hives in Norfolk UK having started keeping bees again only this year and it seems likely the Asian Hornets will spread across the country as varroa did. I have my hives at the end of our garden so like Michael I’m able to go and visit them several times a day when I’m home. (Is this why I’m not getting much else done??)
Sue,
Bees are certainly the reason I don’t get anything else done.
We have had a second sighting in the UK. The second one is 25 miles as the crow flies, south of the Bath area. This is not good news.
Philippa,
That is so sad and scary. You’re right, it is really bad news. I expect we will find them over here soon. Any time, really.
I hope for the bees’ sake they don’t ever reach you. Ironically though if they do, you might have a defence. The Africanised honey bee that’s working it’s way up your country may well be able to defend against the hornet due to their increased aggression (?). Who knows?
I wonder if the next generation of honey bee experiments will be to cross the European honey bee with the Asian honey bee to introduce the heat balling trait that they carry out to defend their hives? If they do, lets hope there aren’t any other nasty traits that follow.
Here in the UK, I feel our bees are on borrowed time. The introduction of the Buckfast bee to make beekeeping more enjoyable for us humans and allow us to keep bees relatively safely in urban areas may well be our downfall.
Until then though, traps a plenty, entrance guards, vigilance and an electrified badminton racket! It ain’t over yet!!! ☺
I totally agree with you. Although I am not an expert in cross breeding bees etc and your thoughts sound somewhat terrifying to an ordinary guy like me.
I would note that we seem to have two types of bees here (one of them is Italian). In spring I moved three hives of non Italian bees away from my garden. For some reason I kept the Italians ( perhaps a selfish wish to have some bees near me). The resulting changed behaviour from last year is quite astonishing. As you will see on my photo on this blog they formed a line 3/4 wide and the width of the muzzle from the hive entrance to the front of the muzzle. They climbed up the wire and sat and fanned there. They became a landing and take off ramp for bees. They could watch for hornets and actually catch them. They did not form the hot ball but about 6 to 8 bees surrounded the hornet and nearly killed it and sometimes did. The other thing I noticed was that after I had cleared the hornets away with my racquet, the usual guard bees would be as usual on the entrance as one would expect. However a new practice emerged with my lovely Italians. A guard bee would take off and fly virtually all around and even under the hive having a good look for hornets. So it would seem to me that these wonderful creatures are adapting all by themselves to the threat. Don’t you just love them !
Rusty/Michael,
A bit more information literally just released on the fish bait lure from our National Bee Unit:
It is very important that beekeepers remain vigilant and monitor their apiaries and surrounding forage for any Asian hornet activity. At this time of the year, Asian hornets can be seen foraging on the ivy for nectar and preying on other foraging insects for protein.
Traps should also be hung out and closely monitored. When using bait, please refrain from using light beer or lager mixed with sugar as this does not work. In France a Dark beer, mixed with 25ml of strawberry syrup and 25ml of orange liqueur has proven to work well.
Additionally, a protein bait of mashed fish e.g. prawns or trout, diluted to 25% has also proven effective.
So presumably 1 part fish: 3 parts water to make the fish bait lure.
Philippa
Philippa,
I think we are on to something here. It seems apparent to me that different lure mixtures work in different places/temperatures/height above sea level and time of year.
I came home and bought some sardines. I simply cut them up and put them in two of my traps. In two and a half days I caught 12 hornets. Not a great success! My thinking was sardines were the most smelly and all alone would, shall we say, develop more smell!
I used a mixture of white wine, cassis, and apple vinegar in my taps during the summer. This worked very well (I had to regularly empty the traps acounting 50 in two traps ). But the second time I made a mixture up the (in late august) it did not work at all. The hornets diet may have changed to protein or I got the mixture wrong.
I think we need people to give the exact recipes, and the location /temperatures and height above sea level, and what time of year it was when it worked, along with the numbers caught against the numbers seen around the hive.
I am not sure how to achieve this as there does seem to be times or places that lure mixtures work or don’t work.
Michael
Philippa,
It is terrible to read that another nest has been found. Sadly, I am afraid that there being only one nest in the area was a forlorn hope. What must be good news is that the Bee Unit is actually finding nests. People in this part of the world only seem to find nests when the leaves fall and all the hornets have long since gone (and mated queens into their winter resting place). As a result UK beekeepers are informed and can try to prepare themselves. My heart goes out to everybody there.
On another note I got home yesterday after my long weekend in London. I had a badminton frenzy and bought a few sardines. I put cut up sardines into two traps and by the evening I had caught one hornet. Hopefully the sardines will become more smelly and I will be able to report more captured hornets.
As the Bee Unit points out, it is important to find where the founding queens are feeding in early spring. I am sure that the number of hornets attacking my hives is down this year because I caught a lot in April.
I am sorry to say that the battle is won but the war will go on.
You have my hopes and best wishes.
Michael
Philippa and Michael,
Even with regular yellowjackets (which you call wasps) I have found that killing queens in the spring gives me the best results in autumn. With fewer nests, the density of predators goes way down. If I had to deal with Asian hornets, that is the first thing I would try.
Rusty,
Firstly, I thought yellowjackets were quite large and probably the American equivalent to our European hornet. Anyway. I absolutely endorse what you say about putting traps out in spring. The important thing is to find a place that they go to feed in spring and put out traps. I did this exactly that last spring and the result was significantly less Hornets later in the year. BTW the French say they got the same results as well.
Michael,
Lots of things are called yellowjackets, but most are about the size of honey bee or a smaller.
I am sad that this is another foe we bees and beeks have to face but in reality it’s just another in a long line of “disasters” that have threatened us over the years. Don’t forget Isle of Wight disease that wiped out thousands of colonies early last century or the tales of woe that arrived with Varroa.
All have been dealt with by changes in husbandry. Let’s hope that this will be the same. Now where is my badminton raquet ?
Rusty/Michael,
Thank you both. I’ll be setting up some smelly fish bait traps myself as well as using my Apishield hornet/wasp traps this weekend. I’ve bought some more of the Apishield traps as this second discovery is only a handful of miles from my ‘out’ apiary so the bees are kinda on their own as I only visit once a week. I feel that where I live we could be in the epi-centre (Avonmouth docks only being a few miles from Bristol and possibly brought them in on a shipment). I am grateful that the National Bee Unit is pulling out all the stops and I am trying to encourage my company (the local water company) to put up traps as we have lots of sites around both areas where the hornets were discovered. I’ll keep you posted if there is any more news as it seems there are quite a few Brits that follow your blog Rusty.
Kind regards,
Philippa
Michael,
Let me know how the sardine solution works. I’m going to try some prawns as they are known to pong!
On another note, as part of your experiments with you Beekeeper friend, is it worth trying one of the Apishield wasp/hornet traps that I posted earlier? I’ve got 4 which I place on my sentinel hives (and therefore more exposed) in both apiaries – perhaps it may help to protect your last hive in your back garden. The traps use dummy entrances so the hornets enter what they think is an unprotected entrance and can’t get out and die of dehydration. This also means that they can’t get back to the hornet nest to inform the others of the nearest honey bee entrees!
Just a thought as I have no idea if they work on the hornets but they are great at catching wasps/yellow jackets – would be good to have some proof before I go buying a load more!!!
Philippa
Rusty /Philippa,
I can now report a little on the fish bait. For the first 3 days I seemed to catch about 12 Hornets, although on a body count it did not come to that number. Puzzling ! I then mashed up the sardines and added a proportion of water. In the two following days I believe I caught one. Not very good.
This is inconclusive as I believe that something else happened at the same time. The weather changed. I am not sure of the conclusions but report my observations. Quite suddenly cloudy and a little stormy and much cooler weather arrived. Day time temperatures went down to less that 20 deg C and night time to 10/12 deg C. This for this month is quite extreme and not expected until November. Mosquitoes all but disappeared. It has been widely reported that further North in the Alps that snow has fallen at altitude. ( this is very early) A cold Winter has also been forecast. Above all the Hornets seemed to melt away. Yesterday morning I went racquet in hand 5 times to the hive in the garden and in total only saw 2 hornets. For several days now I have seen less and less hornets.
The weather forecast for Bristol tomorrow is for 15 deg C day time and 5 deg C at night. I wonder if people in Philippa’s area are still seeing Hornets? I suspect not.
My feeling is that the threshold of temperature has arrived here and that the hornets will die off leaving the mated Queens to find a place to survive the winter.
Dear Michael,
Thank you for your excellent article. I want to write an article in my
association newsletter about the Apishield floor and its faults. Do beekeepers in
France find they work? Will the hornets enter through the cones (I have heard from
our SBI they don’t like having things touch their wings)? My friend can’t pull out
his tray now as the poor quality wood has swollen and the hive is heavy. One time
the floor came out with the tray along with a load of angry bees and then he
couldn’t get it back fully. Do you kill the hornets in the trap by drowning them?
I wouldn’t like to open it with a few angry hornets in it!
Thanks and best wishes.
Sarah,
Thank you very much, but it is really Rusty who needs the thanks.
I am afraid I have not used or know anyone who has used Apishield. However, I will try to answer your questions as far as possible.
As you know the Asian hornet hovers outside the hive entrance waiting for arriving or departing bees. It is not as far as I can see their preferred method to go into a hive. Although they do sometimes enter a hive, this is only when the colony is not defending its entrance and is probably very weak. The wires on the muzzle (see above) allows them to go through but the wings certainly touch. They seem most reluctant to do that. If they do enter my muzzles they get attacked. So I cannot see the logic behind the shield.
As you see in two of my photos above my bees this year formed a “beard” from the entrance to the outer wires of the muzzle. The “beard” is like a summer beard that drops from the entrance. They use this to watch and as a defensive group should a hornet come too close. They also use it as a landing and take off strip.
I am not sure how they die in my bottle type traps. My thought is that they exhaust themselves trying to get out and fall into the liquid and die.
Finally, yes, opening an Apishield would be somewhat frightening. I often have to wait until trapped hornets are dead before I open the bottle trap to renew the bait liquid.
Good luck
Michael
Hi Phillipa,
I used to live in Malmesbury, married a French girl and moved to France. I’m in my first year of beekeeping I had 3 hives but just lost one, I’m not sure why, the article I just read is really good and have got to use some of these ideas.
I live in a small hamlet called Bemecourt in Normandy, last summer I got my colonies and I’ve had terrible trouble with these hornets, don’t underestimate them they are intelligent creatures I watched one hovering around one of my hives, it would dart forward to try and make the bee’s take off, it had no success so it just turned around and waited for a bee to fly back to the hive. Badminton rackets come in very handy ?. Another good trap is made from a water bottle, cut the top off about 1/4 of the way down, place the piece you just cut inside the rest of the bottle, pierce the top each side and tie a loop to hang it.
We mix cheap red wine with as much sugar to make it fairly thick like treacle they get in but can’t get out.
All the best to all you beekeepers
Kind regard,
Ian
I live in Pennsylvania and this past summer I found a HUGE wasp (about 3-4 inches in size!) eating an apple that had been munched on by a chipmunk and then abandoned. First, I freaked out! But once I regained my composure, I went into the house and grabbed my spray can of PAM. PAM is a cooking spray and I was able to get close enough to spray the wasp’s wings. He dropped immediately to the ground where I stomped the %$# out of him! I think this worked as well as a badminton racquet as I have had practice with aggressive wood borer bees. Maybe this spray would offer these bee-loving beeks another option. Good Luck!
Sherry,
I wish you had a picture! I’ve never seen a wasp that big.
Rusty,
They say that everything is bigger in the USA……..For Sherry’s sake I hope they don’t find elephants there as well.
One also wonders what effect PAM (what ever that has in it) might have on a passing honey bee ?
Lol
Michael
Michael,
I think Pam has vegetable oil and soy lecithin. It probably sticks to the bees wings and weighs them down. Also, it may clog the spriacles (breathing holes).
Rusty,
Here are photos of the latest muzzles that my carpenter beekeeper friend has developed. I have photographed these and as the Asian Hornets are starting to appear I will try them out on some hives here.
BTW as an Asian Hornet update. People here along with myself have not seen many springtime hornets. It has been very dry (no rain for 3 months). The count in traps have been down 90%. They have started nosing around my hives here but only in single numbers. Three quarters of the time I go near the hives I do not see any hornets. Am getting about 2 a day in the numerous traps and my badminton racquet gets about 3 or 4 a day. As to the photos, The first one is as last year’s model with bigger entrance holes. Version 2 is open at the top and bottom and has a slit entrance in the middle. Version 3 is only open at the top. I have more photos if you find these three not clear.
All the best
Michael
Michael,
You can’t upload photos directly to this site. I will email you with directions.
I keep bees in an orchard area and have lost a few hives to yellowjackets in the past. A few years ago I read some research done by a Professor Ifantidis in Greece, and built a version of his trap similar to the European (ApiShield) and New Zealand (Hive Defender) designs. I’ve been using my ‘Hive Help’ for two years with great success on all my hives. The trap doubles as a screened bottom board (which provided decent ventilation in our damp climate) and not only distracts and hold wasps, but wax moths and robber bees. With the help of a sticky pad, it also helps with varroa management. Unlike the European and NZ versions, I have designed mine to allow the continued use of a standard entrance reducer. You can see a demonstration of the trap on YouTube: https://www.youtube.com/watch?v=LLQtzLUM9rk&t=103s
Hi,
I’m British but moved to Normandy 5 years ago. Since last year I have 1 hive. I fed my bees a syrup solution the middle of last week, and generally everything seemed fine. But yesterday whilst collecting apples (I have my hive about 100 m away in our orchard, I noticed a number of Asiatic hornets attacking bees and getting into the hive. I have returned this morning and had closer look at the hive, any bees in the hive seem thoroughly weak and aren’t attacking the hornets at all. I feel it is possibly already too late to save my hive. I’m going to have a good look in the surrounding trees to see if I can at least locate the nest and try the plastic bottle trap.
Sarah
Sarah,
I feel bad for you. From what I’ve heard, those things are vicious.
Sarah,
Can you move the hive to an alternative location a few miles away to give the hive a chance to recover and hopefully away from the hornets?
Philippa
Hi Sarah, for anti-hornet tips and general solidarity I recommend a blog by French Beekeepers Amelia and Koroush: https://afrenchgarden.wordpress.com/tag/asian-hornet/
Observation:
I placed plastic trays (ca. 50 cm x 80 cm) close to my hives, filled with water as a watering hole this last dry summer for my bees. I was surprised to constantly find the bottom covered with dead yellow jacket wasps. By comparison there was the odd honey bee among them, less than a dozen. And maybe they were on their way to honey heaven anyway. The ratio might have been 1 : 20 or 1 : 30 bees : wasps. Don’t know if this would work for the hornets as well. But the effort is next to nothing and maybe worth a try. And if you only caught yellow jackets, who would complain.
Hi.
Thanks everyone for your comments, really helpful. I had a green plastic guard on the front of my hive which is meant to stop the AH getting in, but I stood and watched them for some time on Wednesday and noticed that whilst they can’t get into the hive whilst crawling normally, if they invert themselves and crawl through the gap upside down, they can squeeze through!
Sarah,
I am so sorry to reply so late. I have been a bit ill. I am so sorry for you as I know what it is like. Two things –
One: The muzzles work but the one in “French Garden Blog” blog is far too big. In my opinion it gives the bees too much space to defend. The photos of my muzzles I think on this blog somewhere are much smaller and allow the bees to beard and defend. In fact this year I have made the muzzles even smaller and the hornets really do not go near them.
Two: Prawn bodies in a trap do work remarkably well. I also use a skirt attached under the hive entrance to deny the hornets a space to linger awaiting for a returning bee.
Lastly as I mentioned in July (above) I have seen much less hornet activity this year. I do not know the reason for this, I am just thankful. But one thing I have noticed is that the hornets tend to go for weak colonies. A strong colony with large numbers gives the chance for the bees to have a suitable number of defenders to deter the hornets.
Slightly more worrying and a question for Rusty would be that I noticed European hornets hovering rather than flying by. Although they hover facing the hive where the Asian tends to change the direction they face continually.
Michael
I also live in France and people are testing out many other control methods. My favourite is that they catch the hornet alive. glue wool soaked with insecticide and then let it go. I cant find the olriginal post about it but if i dig it out I’ll post it. You have to do a few hornets, its time consuming but the theory is it will kill the horney nest itself rather than continually having to kill them in front of your hives
https://www.ouest-france.fr/pays-de-la-loire/angers-49000/segre-cette-boite-va-devenir-le-cauchemar-des-frelons-asiatiques-5582359 and this. special traps with queen excluders attached so smaller insects can get back out again
Just found two small nests of Asian hornets in my greenhouse, and a nasty sting on my arm. I am in NW France, Aurillac area. Should I report them, what’s best way to eradicate?
Vivian,
Yes, you should report them to your local agricultural authority, and you should ask them the best way to eradicate.
Hi. Last two weeks asian hornets are attacking my bees in front of the hive. Local university already came and tried a methode out to find the nest which failed. I kill some a few days a week. I seems to notice when temperatures are around 20 degrees celcius and chance of Rain they don’t Come. Could be possible I killed some who were communicating my hives location. Got some nice photos and vids from the beehawking to also my bees reacting to an injured asian hornet. Im try ing out of exposing my bees alot to half dead of these hornets Will improve their defensie strategie as they do not Ball the hornets with enough to sufficate (cook) them. I live in east flanders (Belgium). Close to Ghent.
Kind regards
Great article and posting comments,
I have been living in northern east suburb of Paris, countryside. This year is the first year I have seen these wasps (with giant yellow legs). I love honey and our village has there own bee hives. The racket works well, traps as well but they do not die easily.
Some half cook meat hanging in the trap also works well and I bait the trap by placing some of the mixture next to trap entrance. I have fruit trees and grapes, unfortunately another food source.
These wasps use chemicals to bring more to a food source, I notice that if I do not remove the wasp away from where it was hanging out more appear within 15- 30 min.
When I discard the pieces after a successful backhand with my racket other wasps do not show up.
They also do not like netting, it slows them down.
Good luck!
Just another method rather than swatting and that is a ‘butterfly net’ system. I have used a basic one made from an old flower bulb bag and a wire loop taped to a handle. A friend is making a stronger one for me as this flops about a bit.
Basically just hold the net under them, when hovering in front or near the hive. After a couple of seconds thay ignore it then sharply up and twist and they are trapped in the end. Then spray with household wasp / hornet spray or dunk in a bucket of water. Quick and easy and you don’t have to get too close, broom handle would do, I have a piece of metal tube 1.5m long.
They turned up on an empty hive right next to my bees (wild colony left to their own devices) which I don’t regularly visit. They live in an old hive so near the ground as were the asian hornets in this case. I am in France and local pest controller dealt with them, still some coming though so more nearby but no idea where. Policy here is obligatory to report them and the government will destroy them, on your land and here we have to pay half the cost (only 45 euros) but well worth it I would have paid it all.
I have the system of lots of bits or string hanging down and it works a bit (like haveing waving grass in front) but will now do the muzzle, and edge ‘skirt’ below it, and the dangling string (bees fly through it as hornets move to catch them it gets in the way).
Well done John,
I am afraid that it is a constant battle. I discovered this year that although these methods certainly do slow the Hornets down and mostly allow the bees to fly and therefore stave off eventual starvation. If there are more than about 5 hornets per hive that is curtains for the hive.
Last year I had minor problems and survived. This year is totally different. I was forced to move all my local hives 30 Kms away to a location that is 1000 meters high. The difference in performance was extraordinary. Within hours the bees were really flying, so much I had to add more supers, very quickly.
I have been lucky that I found a location without hornets. I wish you all the very best. If you want to know anything , please ask
Michael
Rusty,
I have heard of these hornets, but just in passing. I appreciate having a better understanding of their behavior and possible defenses. Hopefully will be a long while before they are seen here in SW Ohio.
I see the original post was from Sept 2016. Could you add a date to the update?
Thanks again!
Alice,
Oh yes, good idea. Done.
What Mr. Judd’s strategy is referring to is often called “defense in depth.” As were no one barrier is perfect, but with many good barriers very few paths of defense, barrier fail. A good analogy is slices of swiss cheese. Each slice has some holes but all stacked up, there are only a few very small holes where the barrier is passable.
I am somewhat confused as to how to respond to Matt S.
So let me say this. The problem of Asian hornets has certainly not gone away. Here where I live these hornets are still very much in evidence and beekeepers need and are being very vigilant. If we are not then we will lose our colonies. These hornets are clever and very adaptable and change their methods. Indeed I have seen European hornets attempt to hover like the Asian ones. Good luck where ever you are. My advice to expel in the American continent is to watch “yellowjackets” who may be distant cousins but if they see the Asian variety working they could themselves change their methods to the detriment of N. American beekeepers.
Michael
As I read this, I found myself wondering why the muzzle was made with a single layer of .5” mesh rather than using smaller mesh, or 2 layers of .5” mesh offset. Since the AGH are so much bigger, it would seem that making the holes big enough for worker bees, but hopefully, not hornets would be a useful strategy.
Arguing against this plan is that drones would be kept inside the hive, and by extension, if everybody utilized this strategy, requeening would be a problematic proposition.
Also, the Asian hornets can snatch bees out of the air; they don’t need to go inside.
I have had these return and have now converted to the ‘Lyre’ system. The 10-13mm mesh is way too small as is the small muzzle format. The hornets can walk in anyway so it only impedes the bees.
The video shows a good muzzle size, I would say a minimum size maybe a little larger say 40cm deep/high. Wire, or string, spacing about 3cm but play around with it, hornet wingspan is 40cm? Being in the cage puts the hornets off, bees don’t notice the two vertical lines so enter much faster than even chicken wire. Pushes the hornets back a bit, I would also use the wires at the sides and below (no solid or small wire bits) as it gives the bees options.
Simple premise, rough example hive entrance 30cm x 1cm muzzle 30cm x 30cm high = 30x more area to exit through. Add insides and top and makes for better odds, like a goalkeeper protecting a goal 10x normal size. 🙂
Just a link to details and photos of my latest AH muzzle attempt. Some success as the AH sits outside it and it gives the bees the ability to exit in all directions and they do. Makes the AH (only one at a time currently) work for their meal, hoping they will look elsewhere. The main point is the bees don’t seem pinned down as it is not 5 cm from them anymore.
The main thing is it in a ‘Lyre’ type of vertical strings which are hessian material which is softer and not as tensioned as wires. Cheap to make especially in 30 mm wood. Just fyi in case you want to try it, onedrive pdf contains links to video of muzzle that inspired my one in action.
https://1drv.ms/b/s!AgZCpYNgfmp7hBO3QTTC27GaD5Iy?e=oQMEa8
Thanks, John.
Michael (and others) you may be interested in the information in this group I have started. Main thing is it is aimed primarily at providing useful basic information so I am looking more for people sharing working systems and ideas than general discussion.
People can discuss experiences and debate AH in general and any working ideas will be distilled into the ‘Sticky’ posts. People have had some clever ideas, such as freezer baskets, but I am still happy with my larger 30 cm deep string (not wire) strung ‘Lyre’ muzzles. So far so good. I feel the hessian string is kinder to the bees as they occasionally hit it. Just tight enough to be straight, not like a guitar string. Some work to do on size but so far 30 cm deep seems to work, basically, bees are not inconvenienced but Ah are.
I will be posting some videos of the AH when I get organized. They sit outside it, occasionally enter and quickly leave, and the bees behave normally. I have even had small orientation flights with a hornet outside, I only have one at any time though, and think I lose 4-5/hr so am lucky so far.
On that note what I am trying to refine, being in the eye of the storm here in central France, is rough predation dates. I found one article that says they appear in strength 40 days after the first one seen generally on plants etc. Sounds right and I would like to build on that with more specific months rather than just spring summer autumn.
People can join if only to get updates from comments. I don’t expect there to be a lot of that but if a current idea changes you would then know. Or just check in every so often as I put the last updated date on the main page if Stickies change.
https://groups.io/g/asianhornet-beehiveprotection
Charentejohn,
This is Michael Judd responding to your post (on Honey Bee Suite).
I am very happy to join your conversation group and this message will be posted there too.
First, for readers of Honey Bee Suite who are not necessarily in France as you and I are, this is very important as it is important to distinguish between the European Hornet and the Asian Hornet found in France and the new addition to the west coast of the USA of the Asian Giant Hornet. So I can only talk about The Asian hornet and the European Hornet.
Second, for the hornets in France, I use muzzle wire of 13MM square. Some of the photos I see on your new site are far too big.
Third, I have always advised that a European hornet flies like a jet airliner and grabs a bee while passing the hive. The Asian Hornet hovers like a helicopter in front, by the side, or under a hive.
Four, one hornet, and up to about 4, is really no problem to a strong bee hive. But more than 5 will eventually starve the colony to death or make them swarm to escape the siege. I have also noticed European hornets starting to learn to hover.
I am more than happy to answer more questions or enter into discussion on this subject.
Michael Judd
Michael, seems there are more European hornets mimicking the Asian ones as they are competing for other prey; haven’t seen it myself but others have.
I had just a couple and no problems as strong hives but as you say 3-4 and they start to weaken hives due to ‘foraging paralysis’ as well as predation, if they weaken they are likely to die out. Being trapped inside is considered to be the worst aspect. Not a fan of the smaller mesh as it just inconveniences the bees as hornets take them in the air mostly on their return, they have to slow down to land. I am personally more concerned that the bees move freely and the AH are inconvenienced. With the 25mm spaced ‘lyre’ muzzles the bees arrive at full speed to the landing board.
I started with the cube lyre muzzle till autumn when the AH started to enter it and considering landing. I then added a 25mm chicken wire small muzzle and entrance reducer to deter that. All still experimental, Fred Soulat has many such https://www.youtube.com/channel/UCkjZgHJcLBhr4Oc3U-n0Xkg Looks like he was hit hard late in the year and they went through most defenses, once on their radar, it is damage limitation. Masking the smell of the hive is one new option.
Hi everyone, how do you think the laser can be useful for protecting bees from Asian hornets?
https://github.com/Ildaron/Laser_control
you can write me – ildarr2016@gmail.com
Just an update on this as it was last year when I posted and now I have an ‘action’ camera so some video of how my muzzles are doing. https://www.youtube.com/watch?v=J_XjT7Oy2GA&list=PLI–zUmZS0FLeiUbrwqXyX_gz0e7xTiIb There are 3 videos in all.
Just went out today and saw two harassing them, outside the muzzle so ok but they caught one quickly so camera on again. Handy as I leave it for an hour or two then fast forward on the PC to see if I can spot any.
This guy has come up with a cheap way to make lots of muzzles using 25-30mm fence wire, just cut out some horizontals to give a ‘lyre’ effect. Or remove them and add string to make the verticals, his Museliere no 4 is his best I think. Solid top not needed just same fence mesh.
I made one with 80x120mm mesh and just tied strings to make the 25mm gaps. Just a cheaper way if you have lots of hives. You can see the quick one I made when I saw one at my tree hive https://www.youtube.com/watch?v=9REOquMK9MI&list=PLI–zUmZS0FI-WdwDQ2bFYt5nSDHU8WS9&index=2 not pretty but it helps.
Wow, thanks for all the information and visuals. I wonder if these would work with our so-called murder hornets. I believe they are closely related.
The thing about our Asiatic hornets is that one or two are not a problem. The problem arises when you get in excess of 5 hornets in front of one hive. I have not seen the very large one in the Western USA so I have no knowledge. I will offer this on the Asiatic hornet in France that a Museliere gives the bees a space and a possibility to see where the danger is and so choose to fly in a different direction. The other side of this is returning bees laden and tired are much easier to pick off. In my view therefore that the more space and ability to take off and return the better. Good luck Michael
Latest video on hornets, just bits showing hornet activity, only 3 at any one time https://www.youtube.com/watch?v=jbc94G8iNkU&t=362s
Michael is right about picking off bees as you can see them doing it. The best angle I could find to show how far from the muzzle they hover, chasing back and forth. Some catch one quickly but one took 4 mins which is often the case, you can see a couple hit the strings chasing bees. They are all moving freely and I think I lose 10-12/hr for a few hours each day.
On the giant hornets, as ever can’t find it now, but I saw a video from Japan saying their hives have 8mm high entrance, and Japanese bees go inside if a lot of hornets arrive until they leave. European bees come out to defend and are killed off, they regularly lose such hives. The balling and cooking works but is energy intensive so only for the odd one I think.
Only thing I can think of for those would be a chicken wire cage (25mm 1″) mesh over the whole hive like a tent to keep the Mandarina ones away, just a guess and worth a try?